Engineering the mechanical and physical properties of organic–inorganic composite microcapsules

Double-shell composite microcapsule with a ripened CaCO3 nanoparticle outer shell and melamine formaldehyde (MF)/copolymer inner shell shows advantages in adjustable permeability and mechanical strength, comparing with single shell microcapsules. Here, we have systematically studied the effects of certain formulation parameters on the properties of the double-shell composite microcapsules, i.e. the MF cross-linking time and the concentration of the aqueous CaCl2 and Na2CO3 used for the ripening process of CaCO3 nanoparticles. The properties of the microcapsules such as average diameter, wall thickness, degree of wall formation formed by the ripened CaCO3 nanoparticles, nominal rupture stress and leakiness were characterized.